Trả lời:
2 I think the cities are too crowded because it is growing rapidly and attracting a lot of people to live.
3 The cities pollutes the environment ( noise pollution, air pollution,...)
4 we should:
  1 Plant trees and green hills to absorb CO2 as well as toxic substances.
  2 Prioritize the use of public transport, reduce the amount of emissions emitted every day.
  3 Urbanize properly, limit fine dust PM 2.5.
  4 Treat exhaust gas before discharging into the environment.
  5 No littering.